+// printf ("before get: head %3d tail %3d running %d\n", ao_adc_ring_head, ao_adc_ring_tail, ao_adc_running); flush();
+ rnd = (uint32_t *) ao_adc_get(AO_USB_IN_SIZE); /* one 16-bit value per output byte */
+// printf ("after get: head %3d tail %3d running %d\n", ao_adc_ring_head, ao_adc_ring_tail, ao_adc_running); flush();